Wireless charging retail systems

ABSTRACT

A wireless charging table comprising a table top having an upper surface upon which one or more electronic devices can be placed, a wireless charging transmitter positioned under the upper surface of the table top, the wireless charging transmitter comprising a plurality of transmitter coils that define a charging region at the upper surface of the table top, and a power distribution system operatively coupled to the wireless charging transmitter, the power distribution system configured to receive power from an alternating current (AC) power source and distribute power to the wireless charging transmitter. The plurality of transmitter coils include at least a first transmitter coil comprising: a first loop portion; a second loop portion; and a crossing portion comprising overlapping conductive paths that electrically couple the first loop portion.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. ProvisionalApplication No. 62/180,553, filed Jun. 16, 2015, which is herebyincorporated by reference for all purposes.

BACKGROUND

Electronic devices (e.g., mobile phones, media players, electronicwatches, and the like) operate when there is charge stored in theirbatteries. Batteries charge when the electronic device is coupled to apower source, such as via a charging cord. Using charging cords tocharge batteries in electronic devices, however, requires the electronicdevice to be physically tethered to a power outlet. In areas where thereare many devices that are charging, there may be a large, disorganizedgrouping of cables that could easily get tangled. Additionally, usingcharging cords requires the mobile device to have a receptacleconfigured to mate with the charging cord. The receptacle is typically acavity in the electronic device that provides avenues within which dustand moisture can intrude and damage the device. Furthermore, a user ofthe electronic device has to physically connect the charging cable tothe receptacle in order to charge the battery.

To avoid such shortcomings, wireless charging stations have beendeveloped to wirelessly charge electronic devices. Electronic devicesmay charge by merely resting on a charging surface of the chargingstation. Magnetic fields generated by transmitters disposed below thecharging surface may induce corresponding currents in receivers thathave a corresponding inductive coil. The induced currents may be used bythe electronic device to charge an internal battery.

Existing wireless charging systems have a number of disadvantages. Forinstance, wireless charging surfaces require a specific charging regiondisposed on top of a transmitter coil embedded beneath the surface. Thisrequires the electronic device to be placed in a very specific area onthe charging surface. If an electronic device is placed outside of thecharging region, the electronic device may not wirelessly charge due tothe absence of a magnetic field. Additionally, since single axismagnetic fields require transmitter and receiver coils to be disposed onparallel planes, the electronic device must be positioned in aparticular orientation (e.g., with the back face of the device restingon the surface) in order for charging to occur.

SUMMARY

Embodiments provide transmitters, receivers, and systems for wirelesscharging. Embodiments further provide methods of making receivers andmethods of wireless charging.

In some embodiments, an array of transmitter coils can be disposed belowa charging surface. The array of transmitter coils may generatetime-varying magnetic fields across a vast majority of the chargingsurface. The magnetic fields can provide power to a dock (or electronicdevice) located at virtually any position of the surface and in anyorientation by inducing current in a multi-dimensional receiver coil ofthe dock (or electronic device).

In some embodiments, a wireless charging transmitter includes a coilconfigured to transmit power. The coil may include a first loop portion,a second loop portion, and a crossing portion. The crossing portion mayinclude overlapping conductive paths electrically coupling the firstloop portion and the second loop portion. The first and second loopportions may be electrically coupled such that, when an electricalcurrent is generated in the coil, the electrical current flows throughthe first loop portion in a first rotational direction, and through thesecond loop portion in a second rotational direction different than thefirst rotational direction.

In some embodiments, a wireless charging transmitter includes: a coilconfigured to transmit power, the coil including a first loop portion; asecond loop portion; and a crossing portion comprising overlappingconductive paths that electrically couple the first loop portion and thesecond loop portion such that, when an electrical current is generatedin the coil, the electrical current flows through the first loop portionin a first rotational direction and through the second loop portion in asecond rotational direction opposite the first rotational direction.

The first loop portion and the second loop portion may be characterizedby substantially the same shape and dimensions. In certain embodiments,when the electrical current is generated in the coil a first magneticfield may be generated by the electrical current flowing through thefirst loop portion, the first magnetic field being characterized by afirst direction; and a second magnetic field may be generated by theelectrical current flowing through the second loop portion, the secondmagnetic field being characterized by a second direction different thanthe first direction. An angle formed between the first direction and thesecond direction may be at least 135 degrees. In some embodiments, thefirst direction and the second direction may extend in oppositedirections. The crossing portion may be a first crossing portion, andwherein the transmitter may further include a second coil configured totransmit power, the second coil including: a third loop portion; afourth loop portion; and a second crossing portion comprisingoverlapping conductive paths that electrically couple the third loopportion and the fourth loop portion such that, when an electricalcurrent is generated in the second coil, the electrical current flowsthrough the third loop portion in the first rotational direction andthrough the fourth loop portion in the second rotational direction. Whenthe electrical current is generated in the first coil and the secondcoil, a bridging magnetic field may be generated in a region between thefirst coil and the second coil. In certain embodiments, the bridgingmagnetic field may bend between the second loop portion and the thirdloop portion. The bridging magnetic field may bend in an orientationfrom the second loop portion to the third loop portion. In particularembodiments, the bridging magnetic field may bend in an orientation fromthe third loop portion to the second loop portion. The second coil mayoverlap at least a portion of the first coil. In some embodiments, thefirst loop portion may have a first horizontal part and a first verticalpart, and the second loop portion may have a second horizontal part anda second vertical part. The first horizontal part may extend above thesecond vertical part, and wherein the second horizontal part extendsbelow the first vertical part.

In some embodiments, a wireless charging receiver includes: a first coildisposed relative to a first axis; a second coil disposed relative to asecond axis, the second axis extending in a direction different than thefirst axis; and a ferromagnetic structure positioned adjacent to thefirst coil and the second coil.

The wireless charging receiver may further include a third coil disposedrelative to a third axis, the third axis may extend in a directiondifferent than the first axis and the second axis. The second axis mayextend in a direction between 45 to 135 degrees from the first axis, andthe third may extend in a direction between 45 to 135 degrees from thefirst axis and the second axis. In some embodiments, the second axis maybe perpendicular to the first axis, and the third axis may beperpendicular to the first axis and the second axis. The first coil maybe disposed around the ferromagnetic structure, and the second coil maybe disposed around the ferromagnetic structure and the first coil. Insome embodiments, the third coil may be disposed around theferromagnetic structure, the first coil, and the second coil. Thewireless charging receiver may further include a first insulating layerdisposed between the ferromagnetic structure and the first coil, asecond insulating layer disposed between the first coil and the secondcoil, and a third insulating layer disposed between the second coil andthe third coil. The first coil may be disposed along the first axis, andthe second coil may be disposed along the second axis. In someembodiments, both the first coil and the second coil each comprise a twoloop portions. The ferromagnetic structure may be a shielding diskpositioned above the first coil and the second coil.

In particular embodiments, a method of fabricating a wireless chargingreceiver includes: providing a ferromagnetic structure; forming a firstinsulating layer around the ferromagnetic structure; forming a firstcoil on the first insulating layer, the first coil being disposed abouta first axis of the ferromagnetic structure; forming a second insulatinglayer on the first coil and exposed surfaces of the first insulatinglayer; forming a second coil on the second insulating layer, the secondcoil being disposed about a second axis of the ferromagnetic structure,and the second axis being substantially perpendicular to the first axis;forming a third insulating layer on the second coil and exposed surfacesof the second insulating layer; and forming a third coil on the thirdinsulating layer, the third coil being disposed about a third axis ofthe ferromagnetic structure, and the third axis being substantiallyperpendicular to the first axis and the second axis.

In certain embodiments, forming the first coil, the second coil, and thethird coil each includes depositing a patterned layer of conductivematerial. The first insulating layer may be formed by fusing a first setof two halves together over the ferromagnetic structure, where thesecond insulating layer may be formed by fusing a second set of twohalves together over the first insulating layer and the first coil, andwhere the third insulating layer may be formed by fusing a third set oftwo halves together over the second insulating layer and the secondcoil.

In some embodiments, a wireless charging system includes: a transmitterassembly comprising: a charging surface; and a plurality of transmittercoils disposed below the charging surface. The plurality of coilsinclude first and second transmitter coils configured to transmit power,the first coil generating first and second magnetic fields and thesecond coil generating third and fourth magnetic fields when driven withelectrical current, the first and second transmitter coils forming abridging magnetic field disposed between the first and secondtransmitter coils; and a receiver assembly. The receiver assemblyincludes: a first coil disposed relative to a first axis; a second coildisposed relative to a second axis, the second axis extending in adirection different than the first axis; and a ferromagnetic structurepositioned adjacent to the first coil and the second coil.

The wireless charging system may further include a third receiver coildisposed relative to a third axis, the third axis being substantiallyperpendicular to the first axis and the second axis. The chargingsurface may be substantially planar. The charging surface may includecurved regions. In certain embodiments, the bridging magnetic field maybend between the second and third magnetic fields. A fifth magneticfield may bridge between two loop portions of the first transmittercoil, and a sixth magnetic field may bridge between two loop portions ofthe second coil. Each transmitter coil may have a length and a width,where the length may be correlated with a dimension of the chargingsurface. The length may be twice the width.

In some embodiments, a wireless charging table includes: a table tophaving an upper surface upon which one or more electronic devices can beplaced; a wireless charging transmitter positioned under the uppersurface of the table top, the wireless charging transmitter comprising aplurality of transmitter coils that define a charging region at theupper surface of the table top, the plurality of transmitter coilsincluding at least a first transmitter coil including: a first loopportion; a second loop portion; and a crossing portion comprisingoverlapping conductive paths that electrically couple the first loopportion and the second loop portion such that, when an electricalcurrent may be generated in the first transmitter coil, the electricalcurrent flows through the first loop portion in a first rotationaldirection, and through the second loop portion in a second rotationaldirection opposite the first rotational direction; and a powerdistribution system operatively coupled to the wireless chargingtransmitter, the power distribution system configured to receive powerfrom an alternating current (AC) power source and distribute power tothe wireless charging transmitter.

When the electrical current may be generated in the first transmittercoil: a first magnetic field may be generated by the current flowingthrough the first loop portion, the first magnetic field beingcharacterized by a first direction; and a second magnetic field may begenerated by the current flowing through the second loop portion, thesecond magnetic field being characterized by a second directiondifferent than the first direction. In certain embodiments, an angleformed between the first direction and the second direction may be atleast 135 degrees. The crossing portion may be a first crossing portion,and where the plurality of transmitter coils further includes a secondcoil configured to transmit power, the second coil includes: a thirdloop portion; a fourth loop portion; and a second crossing portioncomprising overlapping conductive paths that electrically couple thethird loop portion and the fourth loop portion such that, when anelectrical current may be generated in the second coil, the electricalcurrent flows: through the third loop portion in the first rotationaldirection; and through the fourth loop portion in the second rotationaldirection. When the electrical current is generated in the firsttransmitter coil and the second coil, a bridging magnetic field may begenerated in a region between the first transmitter coil and the secondcoil. The bridging magnetic field may bend between the second loopportion and the third loop portion. In some embodiments, the first loopportion may have a first horizontal part and a first vertical part, andthe second loop portion may have a second horizontal part and a secondvertical part. The first horizontal part may extend above the secondvertical part, and the second horizontal part may extend below the firstvertical part. The power distribution system may include a controllerconfigured to communicate with an electronic device of the one or moreelectronic devices.

In some embodiments, a wireless charging receiver for interacting with awireless charging retail table includes: a first coil disposed relativeto a first axis; a second coil disposed relative to a second axis, thesecond axis extending in a direction different than the first axis; anda ferromagnetic structure positioned adjacent to the first coil and thesecond coil, where the first coil, the second coil, and theferromagnetic structure are configured to receive magnetic fieldsgenerated by a transmitter for the wireless charging retail table.

The wireless charging receiver may be encased within a docking station.The docking station may be configured to rest on a charging surface ofthe wireless charging retail table. The docking station may beconfigured to connect to an electronic device to provide power to theelectronic device. The wireless charging receiver may further include athird coil disposed relative to a third axis, the third axis extendingin a direction different than the first axis and the second axis. Thesecond axis may extend in a direction between 45 to 135 degrees from thefirst axis, and the third axis may extend in a direction between 45 to135 degrees from the first axis and the second axis. The second axis maybe perpendicular to the first axis, and the third axis may beperpendicular to the first axis and the second axis.

In some embodiments, a wireless charging system includes: a table tophaving an upper surface upon which one or more electronic devices can beplaced; a wireless charging transmitter positioned under the uppersurface of the table top, the wireless charging transmitter comprising aplurality of transmitter coils that define a charging region at theupper surface of the table top, the plurality of transmitter coilsincluding at least a first transmitter coil includes: a first loopportion; a second loop portion; and a crossing portion comprisingoverlapping conductive paths that electrically couple the first loopportion and the second loop portion such that, when an electricalcurrent is generated in the first transmitter coil, the electricalcurrent flows through the first loop portion in a first rotationaldirection, and through the second loop portion in a second rotationaldirection opposite the first rotational direction; and a powerdistribution system operatively coupled to the wireless chargingtransmitter, the power distribution system may be configured to receivepower from an alternating current (AC) power source and distribute powerto the wireless charging transmitter. The wireless charging system alsoincludes a wireless charging receiver including: a first coil disposedrelative to a first axis; a second coil disposed relative to a secondaxis, the second axis extending in a direction different than the firstaxis; and a ferromagnetic structure positioned adjacent to the firstcoil and the second coil, where the first coil, the second coil, and theferromagnetic structure are configured to receive magnetic fieldsgenerated by the plurality of transmitter coils.

The wireless charging system may also include a plurality of sensorsconfigured to detect a presence of an electronic device. The powerdistribution system may include a controller coupled to the plurality ofsensors and the plurality of transmitter coils. The controller may beconfigured to selectively energize one or more transmitter coils inresponse to the detected presence of the electronic device. The wirelesscharging receiver may be encased within a docking station.

A better understanding of the nature and advantages of embodiments ofthe present disclosure may be gained with reference to the followingdetailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified diagram illustrating a wireless charging station,in accordance with embodiments of the present disclosure.

FIG. 2A is a simplified diagram illustrating a transmitter coil inaccordance with some embodiments of the present disclosure.

FIG. 2B is a simplified diagram illustrating a transmitter coil inaccordance with embodiments of the present disclosure.

FIG. 3A is a simplified diagram illustrating a pair of transmitter coilsaccording to FIG. 2A arranged in a parallel configuration, in accordancewith embodiments of the present disclosure.

FIG. 3B is a simplified diagram illustrating a pair of transmitter coilsaccording to FIG. 2A arranged in a perpendicular configuration, inaccordance with embodiments of the present disclosure.

FIG. 4 is a simplified diagram illustrating a pair of transmitter coilsaccording to FIG. 2B arranged in a parallel configuration, in accordancewith embodiments of the present disclosure.

FIG. 5 is a simplified diagram illustrating a side-view cross-section ofa wireless charging station, in accordance with embodiments of thepresent disclosure.

FIG. 6A is a simplified diagram illustrating a receiver including a coreand coils wrapped around the core, in accordance with embodiments of thepresent disclosure.

FIG. 6B is a simplified diagram illustrating a receiver including a coreand coils wrapped around the core and disposed underneath the core, inaccordance with embodiments of the present disclosure.

FIG. 7A is a simplified diagram illustrating a receiver including coilshaving oval-shaped loop portions and a shielding disk disposed above thecoils, in accordance with embodiments of the present disclosure.

FIG. 7B is a simplified diagram illustrating a receiver including coilshaving bow tie-shaped loop portions and a shielding disk disposed abovethe coils, in accordance with embodiments of the present disclosure.

FIG. 7C is a simplified diagram illustrating a cross-sectional view of areceiver including coils having loop portions and a shielding disk, inaccordance with embodiments of the present disclosure.

FIG. 7D is a simplified diagram illustrating a cross-sectional view of amagnetic field propagating through a receiver including coils havingloop portions and a shielding disk, in accordance with embodiments ofthe present disclosure.

FIG. 8 is a simplified diagram illustrating a receiver interacting witha transmitter in a wireless charging station in the X and Z directions,in accordance with embodiments of the present disclosure.

FIG. 9 is a simplified diagram illustrating a receiver interacting witha transmitter in a wireless charging station in the X and Y directions,in accordance with embodiments of the present disclosure.

FIG. 10 is a simplified diagram illustrating a charging surfaceconfigured to selectively energize certain transmitters closest to anelectronic device, in accordance with embodiments of the presentdisclosure.

FIG. 11 is a simplified diagram of a stacked transmitter, in accordancewith embodiments of the present disclosure.

FIG. 12 is a simplified diagram illustrating a cross-sectional view ofan exemplary stacked transmitter and the interaction of its generatedmagnetic fields with a receiver placed in various positions, inaccordance with embodiments of the present disclosure.

FIG. 13 is a simplified diagram of a stacked receiver, in accordancewith embodiments of the present disclosure.

FIG. 14 is a simplified diagram of a charging system including stackedreceivers positioned over a plurality of stacked transmitters, inaccordance with embodiments of the present disclosure.

FIG. 15 is a flow diagram illustrating a method of forming a receiver,in accordance with embodiments of the present disclosure.

FIG. 16 is a flow diagram illustrating a method of charging anelectronic device using a wireless charging station, in accordance withembodiments of the present disclosure.

DETAILED DESCRIPTION

Embodiments describe a wireless charging system where an electronicdevice may be charged across a vast majority, if not an entire area, ofa charging surface. An array of transmitter coils disposed below acharging surface may generate time-varying magnetic fields capable ofinducing current in a receiver of the electronic device or of a dockingstation with which the electronic device is coupled. In certainembodiments, each transmitter coil can generate magnetic fields indifferent directions simultaneously. For instance, each transmitter coilcan generate two magnetic fields in opposite directions. Portions oftransmitter coils may also interact with one another such that magneticfields generated in one portion of a coil can bend into another portionof the same coil.

In some embodiments, magnetic fields generated by each transmitter mayalso bridge between transmitter coils. For instance, magnetic fieldsgenerated by current traveling through a portion of one transmitter coilmay bend into a portion of another adjacent transmitter coil.Accordingly, magnetic fields may be formed between transmitter coilssuch that magnetic fields are present across an entire charging surfaceincluding an array of embedded transmitter coils with little or nodrop-off in field strength above regions in between adjacent coils.

In some embodiments, the receiver can include coils in which current isinduced when in the presence of the magnetic fields generated by thearray of transmitters to generate current for charging electronicdevices. Specifically, in some embodiments, the receiver may beconfigured to utilize the magnetic fields generated by individualtransmitter coils in addition to magnetic fields flowing betweenadjacent transmitter coils to generate current for charging electronicdevices. Details of such a wireless charging system is discussed infurther detail herein.

I. Wireless Charging Station

FIG. 1 illustrates an exemplary wireless charging station 100 inaccordance with some embodiments of the present disclosure. Wirelesscharging station 100 includes a charging surface 102. Charging surface102 may be a surface upon which a device having a receiver may rest towirelessly charge its battery. In some embodiments, charging surface 102may be a top surface of a charging structure (e.g., a table havingcharging surface 102 and a plurality of legs supporting charging surface102) that is substantially planar. In other embodiments, chargingsurface 102 may include curvature such that regions of charging surface102 are substantially non-planar. The curvature may be convex orconcave, or may include multiple convex and concave profiles organizedin a predetermined or random arrangement.

In some embodiments, wireless charging station 100 also includes sets oftransmitters 104 and 106. Sets of transmitters 104 and 106 may eachinclude a plurality of coils. For instance, sets of transmitters 104 and106 may each contain N number of coils as illustrated in FIG. 1. Thenumber N may be any suitable number capable of allowing the set oftransmitters to generate magnetic fields across a vast majority, if notthe entire area, of charging surface 102. In embodiments, sets oftransmitters 104 and 106 may be disposed underneath charging surface 102and embedded within charging station 100. Although embodiments discusstwo sets of transmitters 104 and 106, other embodiments are not limitedto such arrangements. For instance, embodiments may be formed of more orless than two sets of transmitters.

In certain embodiments, sets of transmitters 104 and 106 may haveidentical coil arrangements. In other embodiments, sets of transmitters104 and 106 may have different coil arrangements. For instance, set oftransmitters 104 may have more or less coils than set of transmitters106. Furthermore, set of transmitters 104 may have a different coilarrangement (e.g., perpendicular or parallel arrangements) than set oftransmitters 106, as will be discussed further herein with respect toFIGS. 3A and 3B.

Magnetic fields may be generated by each of the coils in sets oftransmitters 104 and 106 when a time-varying current is generated in thecoils. For instance, each coil may be configured to generate atime-varying magnetic field when an AC current is generated in the coil.In some embodiments, the aggregate time-varying magnetic fieldsgenerated by the sets of transmitters 104 and 106 at charging surface102 may create charging regions 108 and 80 that span across a vastmajority of charging surface 102. For instance, in some embodiments,charging regions 108 and 80 may occupy 50% to 100% of the total surfacearea of charging surface 102. In FIG. 1, a gap is shown between chargingregions 108 and 80. This, however, is not intended to be limiting. Insome embodiments, magnetic fields generated by set of transmitters 104and set of transmitters 106 can overlap (or even travel between eachset) at charging surface 102.

Wireless charging can occur when a receiver is placed on or nearcharging surface 102. The receiver may be disposed within a receivingdevice 112, such as an electronic device that can be charged directly bythe receiver or a docking station that can use energy received by thereceiver to charge another electronic device operatively coupled to thedocking station. For example, if the receiver is disposed within adocking station, an electronic device to be charged may be operativelycoupled to the docking station by a physical connector through whichcharge from the docking station can be transferred to the electronicdevice. In some embodiments, an electronic device may receive power fromthe docking station via a second, separate inductive charging system.That is, the docking station can include both a first receiver towirelessly receive energy from one or more of transmitters 104, 106 anda docking station wireless transmitter that wireless transmits energyfrom the docking station to a second receiver in the electronic device.

When receiving device 112 is placed on charging surface 102,time-varying magnetic fields generated by one or more coils in the setsof transmitters 104 and 106 may induce a current in the receiverdisposed within the receiving device 112. The induced current may thenbe rectified by the receiving device 112 to generate DC power and chargea battery. Due to the continuous magnetic fields generated acrosscharging surface 102, receiving device 112 can generate power whenplaced on virtually any region the charging surface 102. Unlikeconventional wireless charging arrangements, receiving device 112 cangenerate power even when it is located between coils, such as betweencoils 104-1 and 104-2, due to magnetic fields traveling between coils.In embodiments, another receiving device 116 may also generate powerwhen placed above a coil, such as coil 104-3, because magnetic fieldsgenerated by coil 104-3 may exist there as well. Additionally, thereceiver of receiving device 112 can be configured to receive power inthe form of magnetic fields generated in virtually any direction,thereby allowing receiving device 112 to be placed on charging surfacein many different orientations. Details of the transmitter and receiverdesign that can facilitate such charging capabilities will be discussedfurther herein.

II. Transmitter

In embodiments of the present disclosure, a “transmitter” may include acoil of wire that generates a magnetic field when current is generatedin the coil. The direction of the magnetic field may depend on therotational direction of the current flowing through the coil (e.g.,clockwise or counter-clockwise). For instance, according to the righthand rule (RHR), a counter-clockwise flow of current will generate anupward magnetic field inside the coil. Conversely, a clockwise flow ofcurrent will generate a downward magnetic field inside the coil. Theshape and configuration of the coil may directly affect thecharacteristics of the magnetic field generated by the transmitter.

A. Transmitter Coil Structure

FIG. 2A is a simplified diagram illustrating an exemplary transmitter200, according to embodiments of the present disclosure. Transmitter 200may be used in the sets of transmitters 104 and 106 discussed hereinwith respect to FIG. 1. Transmitter 200 may be formed of a coil 202 thatcrosses over itself to form multiple loop portions. For instance, coil202 may form two loop portions: a first loop portion 204 and a secondloop portion 206. First and second loop portions 204 and 206 may besubstantially similar in size and shape. In some embodiments, first andsecond loop portions 204 and 206 may be mirror images of one another. Insome embodiments, coil 202 may comprise one turn (e.g., as seen in FIG.2A). In some other embodiments, coil 202 may have more than one turnswith each turn comprising a first and second loop portion.

In some embodiments, first and second loop portions 204 and 206 may beelectrically coupled together by a crossing portion 208. Crossingportion 208 may be a point at which coil 202 overlaps itself such thatcurrent flowing through first loop portion 204 may continue to flowthrough second loop portion 206. Accordingly, a single current may flowfrom node A to node B through coil 202, as illustrated in FIG. 2A. Insome embodiments, overlapping wire portions at crossing portion 208 maybe insulated from one another to minimize interference and/or preventoccurrence of short circuiting. For instance, coil 202 may be aninsulated wire, or a patterned wire insulated by an insulating layerdisposed between the crossing portion 208.

As a current 210 is driven through transmitter 200, magnetic fields maybe generated by coil 202. As an example, magnetic fields 216 and 218 maybe generated by transmitter 200 as current 210 is driven through coil202. Magnetic fields 216 and 218 may be generated in a directionaccording to the direction of current flow around coil 202 asestablished by the RHR. In some embodiments, the rotational direction ofcurrent flow around second loop portion 206 may be opposite therotational direction of the same current flow around first loop portion204. For instance, nodes A and B can be connected to a power source, andas shown in FIG. 2A current 210 may flow into the coil 202 from node A,across crossing portion 208, around second loop portion 206, acrosscrossing portion 208 again, around first loop portion 204, and out ofthe coil at node B. Thus, a counter-clockwise current flow 212 may beformed in first loop portion 204, and a clockwise current flow 214 maybe formed in second loop portion 206. When the bias of the power sourceis reversed, current can flow through the coil 202 in the oppositedirection, thereby creating a clockwise current flow in first loopportion 204 and a counter-clockwise current flow in second loop portion206.

As a result of the current flow, first magnetic field 216 may begenerated within first loop portion 204, and second magnetic field 218may be generated in second loop portion 206. In some embodiments, firstmagnetic field 216 is generated in a direction different than secondmagnetic field 218. As an example, according to the RHR, when theapplied bias generates current 210 shown in FIG. 2A, first magneticfield 216 may be generated in a direction out of the page (as indicatedby a circle with a dot in the center) due to counter-clockwise currentflow 212, and second magnetic field 218 may be generated in a directioninto the page (as indicated by a circle with an “X” in the center) dueto clockwise current flow 214. When the bias applied by the power sourceis reversed, the change in current direction may generate magneticfields in opposite directions as described herein.

In some embodiments, first magnetic field 216 and second magnetic field218 may be generated in completely opposite directions. Thus, an anglebetween first and second magnetic fields 216 and 218 may beapproximately 180 degrees. However, in some embodiments, first andsecond magnetic fields 216 and 218 may not be generated in completelyopposite directions. This may be because the transmitter 200 is notcompletely flat as a result of manufacturing variations. In suchembodiments, an angle between first and second magnetic fields 216 and218 may be more or less than 180 degrees. In some embodiments, the anglebetween first and second magnetic fields 216 and 218 may be at least 135degrees. In some other embodiments, the angle between first and secondmagnetic fields 216 and 218 may be between 175 and 185 degrees.

Portions of first magnetic field 216 may bridge across transmitter 200.For instance, as shown in FIG. 2A, bridging field 220 of first magneticfield 216 may bend across crossing portion 208 and down into the regionof second magnetic field 218 as a result of the opposite polarity ofmagnetic fields 216 and 218. In some embodiments, bridging field 220 mayextend a distance H away from transmitter 200. Distance H may be setaccording to the distance between transmitter 200 and a charging surfacedisposed above transmitter 200. Distance H may be tall enough to projectabove the charging surface such that a receiver on the surface can bewithin the generated magnetic fields.

In some embodiments, distance H may be altered by changing a distance Dof the first and second loop portions 204 and 206. Distance D mayrepresent the horizontal spacing between edges of a loop portion, suchas loop portions 204 and 206. A greater distance D can result in amagnetic field that projects farther away (e.g., greater distance H).Conversely, a lesser distance D can result in a magnetic field thatprojects closer to transmitter 200 (e.g., lesser distance H).Accordingly, distance D may be designed according to a target distanceH, which may be determined based upon the distance between transmitter200 and the charging surface. The target distance H may be directlyrelated to the thickness of a charging surface. For instance, thickercharging surfaces may require greater distances D. In certainembodiments where, for example, the charging surface is part of arelatively thick upper surface (e.g., between one half inch and twoinches thick) of a charging table sized and shaped to simultaneouslycharge multiple devices, distance D can range between 1 and 12 inches.In a particular embodiment, distance D can be approximately 3 inches fora charging surface approximately 1 inch thick.

As further illustrated in FIG. 2A, embodiments of transmitter 200 mayhave a bow tie shape. That is, portions of first and second loopportions 204 and 206 may taper toward crossing portion 208.Additionally, other portions of first and second loop portions 204 and206 may have a straight-edged profile with relatively sharp corners. Insome embodiments, transmitter 200 may have an overall length L and anoverall width W. In certain embodiments, transmitter 200 may have alength ranging between 1 and 24 inches, such as approximately 6 inches.Overall width W for transmitter 200 may range between 1 and 12 inches,such as approximately 12 inches. In an embodiment, transmitter 200 mayhave a square-shape profile where the length L and width W are equal. Inanother embodiment, transmitter 200 may have a rectangular-shape profilewhere the length L is different than width W. For example, transmitter200 may have a length L that is twice its width W.

Although FIG. 2A illustrates an exemplary transmitter having a bow tieprofile, other profiles are envisioned herein as well. For instance,other embodiments may have curved-edge profiles and/or curved corners.In some embodiments, a transmitter structure may have loop portions thathave a bent profile, e.g., L-shaped loop portions, as shown in FIG. 2B.

FIG. 2B illustrates an exemplary transmitter 222 having loops configuredin a bent, L-shaped profile, according to an embodiment of the presentdisclosure. Similar to transmitter 200, transmitter 222 may be formed ofa coil 224 that crosses over itself to form multiple loop portions,e.g., two loop portions: a first loop portion 226 and a second loopportion 228. First and second loop portions 226 and 228 are electricallycoupled together by a crossing portion 530, which may be a point atwhich transmitter 222 overlaps itself such that current flowing throughfirst loop portion 226 may continue to flow through second loop portion228.

As a current 532 is driven through transmitter 222, magnetic fields maybe generated by transmitter 222. As an example, first and secondmagnetic fields 534 and 536 may be generated by transmitter 222 ascurrent 532 is driven through coil 224. According to the RHR, when theapplied bias generates current 532 shown in FIG. 2B, first magneticfield 534 may be generated in a direction out of the page due tocounter-clockwise current flow 538, and second magnetic field 536 may begenerated in a direction into the page due to clockwise current flow540.

As shown in FIG. 2B, first and second loop portions 226 and 228 havebent profiles. Accordingly, a horizontal part of first loop portion 226may extend over a vertical part of second loop portion 228 as shown inFIG. 2B, and vice versa. Having the horizontal part of first loopportion 226 extend over the vertical part of second loop portion 228causes the left and right edges of transmitter 222 to include parts offirst and second loop portions 226 and 228. Thus, each of the left andright edges of transmitter 222 may generate magnetic fields that extendin opposite directions. The opposite polarity of the magnetic fieldsminimizes detrimental coupling between neighboring transmitter coils, aswill be discussed further herein.

Similar to transmitter 200 in FIG. 2A, transmitter 222 may also have anoverall length L, an overall width W, and a distance D. In someembodiments, the dimensions of each transmitter 222 can be related tothe dimensions of a charging surface. For instance, in an embodimentwhere a charging surface has a length that is two times greater than itswidth, a transmitter 222 can have a length L that is also two timeslarger than its width. Furthermore, the thickness of the chargingsurface may dictate distance D of transmitter 222. A larger distance Dmay result in a magnetic field projecting a greater distance H away fromtransmitter 222. Thus, transmitter 222 may have a distance D rangingbetween 1-12 inches for a charging surface approximately 1 inch thick.In a particular embodiment, the distance D is approximately 3 inches.Accordingly, transmitter 222 may project a magnetic field above acharging surface such that receivers may interact with the magneticfield.

B. Transmitter Arrangement

According to some embodiments, a transmitter having more than one coilmay be used to generate magnetic fields at a charging surface, such ascharging surface 102 in FIG. 1. For instance, more than one coil may beplaced proximate to one another such that a magnetic fields existsbetween the coils.

FIG. 3A illustrates an exemplary transmitter arrangement where two coilshaving bow tie profiles are arranged proximate to one another. As shown,a first coil 301 may be disposed laterally proximate to a second coil302 such that both coils are arranged parallel to one another. Firstcoil 301 may include a first loop portion 304 and second loop portion306. Current 318 flowing through first coil 301 may generate a firstmagnetic field 308 and a second magnetic field 310. A portion 326 ofmagnetic field 308 may bridge between first and second loop portions 304and 306. Second coil 302 may include a third loop portion 312 and fourthloop portion 314. Current 320 flowing through second coil 302 maygenerate a third magnetic field 322 and a fourth magnetic field 324. Insome embodiments, the rotational flow of the current through third loopportion 312 may be the same as the rotational flow of the currentthrough first loop portion 304. Accordingly, a portion 328 of themagnetic field 322 may bridge between third and fourth loop portions 312and 314.

In some embodiments, the direction of the magnetic fields generated byloop portions in adjacent coils may be opposite one another. Forexample, magnetic field 310 generated by second loop portion 306 may bein an opposite direction to magnetic field 322 generated by third loopportion 312. Due to their opposite polarities, a portion 316 of magneticfield 322 may bridge between coils 301 and 302 and bend downward intothe second loop portion 306. Accordingly, a magnetic field may exist ina space X between adjacent coils 301 and 302. In some embodiments, areceiver may generate power when placed on a region of a chargingsurface above a space between coils as well as above the center of acoil , as will be discussed further herein.

In some embodiments, as shown in FIG. 3A, adjacent coils can be arrangedin a parallel configuration. In some other embodiments, adjacent coilscan be arranged in a perpendicular configuration. FIG. 3B illustratessuch a transmitter arrangement where two coils are arrangedperpendicular to one another. As shown, a second coil 332 is arranged atan angle offset from a first coil 331 of approximately 60 degrees. Byplacing the two coils perpendicular to one another, undesirable couplingeffects between adjacent coils can be alleviated in some embodiments.Additionally, coils 331 and 332 may be arranged to have differentgeometries to minimize coupling. In embodiments where there are morethan two coils, the transmitter arrangement may include an alternatinggeometry arrangement between two different coil geometries. Otherembodiments may minimize coupling by isolating resonant components.Isolating resonant components may be performed by turning off thosecomponents that resonate with one another.

Although modifying the transmitter arrangement may decrease couplingbetween transmitters, other modifications may be performed instead. Forinstance, modifying the profile of the loop portions may minimizedetrimental coupling. In an embodiment, transmitter coils may bemodified to have bent L-shaped loop profiles (i.e., profile in FIG. 2B)to minimize detrimental coupling, as will be discussed herein withrespect to FIG. 4.

FIG. 4 illustrates an exemplary transmitter arrangement where two coilshaving bent L-shaped loop profiles are arranged proximate to oneanother. As shown, a first coil 401 may be disposed laterally proximateto a second coil 402 such that both coils are arranged parallel to oneanother. First coil 401 may include a first loop portion 404 and asecond loop portion 406; and second coil 402 may include a first loopportion 408 and a second loop portion 410. As shown in FIG. 4, onlythose parts of second loop portion 406 of first coil 401 that arelaterally adjacent to parts of first loop portion 408 of second coil 402may interact with one another. Thus, less than the entire edge of coils401 and 402 may interact with one another. In some embodiments,approximately half of the entire edges of coils 401 and 402 may interactwith one another. Due to the decreased interaction between first andsecond coils 401 and 402, detrimental coupling may be less than otherinstances where the entire edges of first and second coils areinteracting with one another (e.g., coils in FIG. 3A), therebyminimizing coupling between first and second coils 401 and 402.

Although FIGS. 3A, 3B, and 4 illustrate first/second coils 301/631,302/632, and 701/702 as being substantially identical, embodiments arenot so limited. For instance, first and second coils may have differentcross-sectional shapes and/or have different sizes. Thus, in someembodiments, first and second coils may have different orientations andalso have different shapes. Furthermore, although FIGS. 3A, 3B, and 4illustrate first and second coils 301, 331 and 302, 332 being adjacentto one another, one skilled in the art will understand that atransmitter may have more than two coils. Thus, first and second coilsmay not be adjacent to one another, but be far away from one anotherwith one or more intermediate coils disposed between them. Further, insome embodiments, transmitters may further include ferromagneticmaterial (e.g., ferrite sheet material) used to concentrate magneticfields and direct them in accordance with selected geometry based uponthe arrangement of the receiver described in further detail herein.

In yet other embodiments, a differential coil 412/414 may be disposedaround the outside of each transmitter coil 401 and 402. Differentialcoil 412/414 may enhance the efficiency of magnetic field generation ofeach transmitter coil 401 and 402. Additionally, differential coil412/714 may minimize far-field magnetic fields, but enhance near-fieldmagnetic fields in relation to the z-direction (i.e., the direction intoand out of the page) of transmitter coils 401 and 402. Thus, conductiveentities that are far from the transmitter coils may not be exposed, ornominally exposed, to the magnetic fields generated by transmitter coils401 and 402, while conductive entities that are close to the transmittercoils may be substantially exposed to the magnetic fields.

C. Transmitter Operation

FIG. 5 illustrates a side-view cross-sectional perspective of a chargingstructure 500 that includes an upper charging surface 502 and atransmitter 504 having a plurality of transmitting coils 504 a-504 daccording to some embodiments of the present disclosure. With referenceto a three-dimensional space, Z and X directions of magnetic fields areobservable in FIG. 5, while magnetic fields in the Y direction, althoughexisting in the embodiment of FIG. 5, are not shown for ease ofdescription. Charging structure 500 is illustrated in FIG. 5 as a tablehaving a table top 503 supported by multiple legs 505. In someembodiments, the table can be located in a retail environment and usedto display and charge multiple electronic devices for potentialpurchase. A charging width 506 across charging surface 502 can representall of or less than the upper surface of table top 503 depending on theplacement and number of individual transmitting coils included intransmitter 504. Additionally, in some embodiments, the dimensions ofone or more individual transmitting coils, such as coils 504 a-504 d,are related to the dimensions of charging surface 502 as discussed abovewith respect to FIGS. 2A and 2B.

Although charging structure 500 is shown in FIG. 5 as a table having acharging surface 502 supported by a plurality of legs, it is to beappreciated that charging structure 500 can be any structure having acharging surface 502 upon which an electronic device may be placed. Forexample, in other embodiments, charging structure 500 can be a chargingmat that is sized and shaped for personal use (e.g., to be placed on adesktop or similar surface). Additionally, while coils 504 a-504 d areshown in FIG. 5 as being embedded within table top 503 of chargingstructure 500, in other embodiments the coils can be placed below thetable top or embedded in other portions of charging structure 503 (e.g.,if charging structure 500 is a charging mat, coils 504 a-504 d can beembedded in the mat). In embodiments where coils 504 a-504 b are placedbelow table top 503, table top 503 may include an apron (not shown) thatsurrounds the edges of table top 503 that extend far enough down suchthat coils 504 a-504 b are hidden from view. Additionally, coils 504a-504 d may be embedded within a protective structure (not shown) thatis attached to table top 503 having a single inlet to accept AC power.When current is driven to coils 504 a-504 d, magnetic fields 512 and 514may be generated. Near-field may be maximized and far-field may beminimized to maximize the strength of magnetic fields at chargingsurface 502. As discussed herein, dimension D of the coils as discussedin FIG. 2A, can be designed to maximize magnetic fields in thenear-field regions.

According to some embodiments of the disclosure, magnetic fields 512generated over the transmitter 504, and magnetic fields 514 generatedbetween transmitters 504 can form a charging width 506 that spans acrossa vast majority of the charging surface 502. Magnetic fields 512 and 514can be generated such that at least a portion of magnetic fields 512 and514 are detectable above charging surface 502 across charging width 506.Thus, unlike conventional charging regions, charging width 506 can besubstantially continuous across the surface and allows an electronicdevice to be charged in areas of charging surface 502 where a coil isnot disposed directly underneath, such as regions between coils 504a-504 d.

In some embodiments, coils 504 a-504 d are coupled to a single powersource. The power source may be an AC (or pulsed DC) voltage or currentsource that produces time-varying current. The time-varying current maythus generate time-varying magnetic fields 512 and 514. According tosome embodiments of the present disclosure, a single power source signalmay be provided to coils 504 a-504 d. Additionally, coils 504 a-504 dmay all be driven by a same clock source such that coils 504 a-504 doperate at the same frequency in a single phase. Thus, in someembodiments, there may be no need to create multiple signals havingdifferent phases, as required in a phased-array system where multipleclock sources are used to drive current to an array of antennas.Accordingly, the arrangement of coils 504 a-504 d may result in asimpler magnetic field generation system. In some embodiments, areceiver having one or more coils may be configured to capture magneticfields 512 and 514 generated by transmitters 504, with magnetic fields512 and 514 inducing current in the receiver coils. Details of suchreceivers are discussed further herein.

In some embodiments, coils 504 a-504 d are coupled to more than onepower source. Any coupling arrangement of coils 504 a-504 d and thepower sources for suitable operation of the transmitter is envisioned inembodiments described herein. For instance, coils 504 a-504 b may becoupled to a first power source, and coils 504 c-504 d may be coupled toa second power source. The power sources may all have the sameconfigurations and operate synchronously. Or, alternatively, the powersources may have different types of configurations and operateasynchronously. For instance, the first power source may provide atime-varying current at a different frequency than the second powersource. As an example, the first and second power sources may operate atfrequencies that are offset by one or more kHz from one another.

III. Receiver

In embodiments of the present disclosure, a “receiver” may be anelectrical component including one or more coils of wire in which acurrent can be induced in the presence of a time-varying magnetic field.In some embodiments, a receiver can be incorporated directly into anelectronic device which can use the induced current to charge a battery.In some embodiments, a receiver can be part of a docking stationconfigured to transfer the generated power to a coupled electronicdevice by way of inductive charging or a wired connection.

As described herein, a power source may drive time-varying current to atransmitter coil. In response, the transmitter coil may generate atime-varying magnetic field. The time-varying magnetic field may inducecurrent in one or more coils of the receiver. The current may then beconverted from AC to DC for use in charging a battery of an electronicdevice.

A. Receiver Structure

Unlike conventional receivers that have only one coil for generatingpower from a magnetic field along one axis, a receiver according to someembodiments described herein may have more than one coil for generatingpower from a time-varying magnetic field in more than one direction.FIG. 6A illustrates an exemplary receiver 600 according to embodimentsof the present disclosure. In some embodiments, receiver 600 may includethree coils: a first coil 602, a second coil 604, and a third coil 606.Each coil may be disposed about a core 608 in different directions suchthat current may be induced in at least one of coils 602, 604, and 606when exposed to an anisotropic magnetic field. For instance, as shown inFIG. 6A, first coil 602 may be disposed about a first axis of core 608extending in an X-direction, second coil 604 may be disposed about asecond axis of core 608 extending in a Y-direction, and third coil 606may be disposed about a third axis of core 608 extending in aZ-direction. In some embodiments, each of the first, second, and thirdaxis can be substantially perpendicular to one another. As further shownin FIG. 6A, coils 602, 604, and 606 can be disposed over each other in aparticular order. This, however, is not intended to be limiting as coils602, 604, and 606 can be disposed in any suitable configuration.

In some embodiments, coils 602, 604, and 606 of receiver 600 are woundabout core 608. As shown in FIG. 6A, core 608 may be in the form of arectangular prism in some embodiments. The rectangular prism may havedimensions that range between 1 to 10 mm thick 610, 20 to 100 mm wide612, and 1 to 50 mm long 614. In some embodiments, the rectangular prismmay have dimensions that range between 4-5 mm thick 610, 50-70 mm wide612, and 10-30 mm long 614. In various embodiments, core 608 can haveany other suitable shape and dimensions.

Core 608 may be formed of any suitable material capable of concentratingmagnetic fields. For instance, core 608 may comprise a ferromagneticmaterial such as ferrite in one example. The amount of magnetic materialin the core may be tailored to result in a core that has a magneticpermeability (μ) ranging between 50 and 250, e.g., between 100 and 200.

Coils 602, 604, and 606 may be wound around core 608 any suitable numberof times such that a sufficient power is generated when subjected to amagnetic field. Power may be generated by the induced current and theresulting voltage established by the number of turns. The number ofturns may be a function of a voltage-over-current ratio in acorresponding receiver of an electronic device (e.g., if the receiver600 is disposed in a dock that wirelessly charges the electronicdevice), as well as a configuration of impedance matching networks(i.e., Z matching networks). In some embodiments, coils 602, 604, and606 may be wound around the core between 1 to 10 times, such as 4 to 7times. Each of coils 602, 604, and 606 may be wound around core 608 thesame number of times in some embodiments. In other embodiments, one ormore of coils 602, 604, and 606 may be wrapped around core 608 adifferent number of times than the other coils. Coils 602, 604, and 606may be insulated from one another as well as from core 608. In someinstances, coils 602, 604, and 606 are in the form of insulated wires.In other instances, coils 602, 604, and 606 are formed of patternedwires insulated by layers of insulating material. Details of howreceiver 600 is formed according to some embodiments is discussed inmore detail further herein.

Although FIG. 6A illustrates a receiver 600 as having all three coilswrapped around a core, embodiments are not limited to suchconfigurations. For instance, one or more coils may not be wrappedaround the core. FIG. 6B illustrates an exemplary receiver 620 where onecoil is not wrapped around a core 628. As shown, a first coil 622 may bedisposed about a first axis of core 628 extending in an X-direction anda second coil 624 may be disposed about a second axis of core 628extending in a Y-direction. First coil 622 and second coil 624 can bewrapped around core 628. A third coil 626 may be disposed about a thirdaxis of core 628 extending in a Z-direction but with third coil 626being disposed below core 628. In certain embodiments, a ferromagneticplate (not shown) may be disposed between core 628 and third coil 626.The magnetic plate may help concentrate magnetic fields in theZ-direction to enhance power generation by third coil 626. Any of coils622, 624, and 626 can be disposed adjacent to but not wrapped aroundcore 628.

FIG. 7A is a simplified diagram of an alternative exemplary receiver 710according to embodiments of the present disclosure. Receiver 710 mayinclude three coils: a first coil 712, a second coil 714, and a thirdcoil 716. First coil 712 may be formed of a winding of wire having afirst loop portion 718 and a second loop portion 720, and second coil714 may be formed of a winding of wire having a first loop portion 722and a second loop portion 724. In embodiments, first coil 712 and secondcoil 714 may each overlap itself near a midpoint between respectivefirst and second loop portions 718, 720 and 722, 724. The overlappingwire portions near the midpoint may be insulated from one another tominimize interference and/or prevent occurrence of short circuiting.Accordingly, a single current may flow through both first and secondloop portions of each coil. Additionally, each coil 712, 714, and 716may be electrically isolated from one another such that there is minimalinterference between them.

In embodiments, third coil 716 may be positioned around both first andsecond coils 712 and 714. For instance, third coil 716 may encircle bothfirst and second coils 712 and 714. In certain embodiments, third coil716 may encircle both first and second loop portions 718 and 720 offirst coil 712 and both first and second loop portions 722 and 724 ofsecond coil 714. A diameter of third coil 916 may be greater than thelargest distance between ends of first coil 712 or second coil 714.

In embodiments, first coil 712 and second coil 714 may each be centeredalong an axis. For example, first coil 712 may be centered along firstaxis 728, and second coil 714 may be centered along second axis 730.First and second axis 728 and 730 may be offset from one another at anangle, such as a 90 degree angle as shown in FIG. 7A. In someembodiments, first and second axis 728 and 730 may intersect at a centerof receiver 710 such that loop portions 718, 720, 722, and 724 may bedisposed symmetrically around the center of receiver 710. Inembodiments, third coil 716 may be disposed about a third axis 732positioned through the center of receiver 710 and extending in adirection perpendicular to both first and second axis 728 and 730.

As illustrated in FIG. 7A, first and second coils 712 and 714 may eachhave first and second loops that are arranged in an oval-shaped profile.However, embodiments are not limited to such profiles. For instance,first and second loops may have profiles that are non-oval, circular,square, rectangular, or any other loop profile. As an example, first andsecond coils 712 and 714 may have first and second loop profilesarranged in a bow tie profile, as shown in FIG. 7B, which illustrates anexemplary receiver 711. Receiver 711 may have a first coil 734 and asecond coil 736. Similar to FIG. 7A, a third coil (not shown) mayencompass first and second coils 734 and 736. In some embodiments, thethird coil is substantially planar with first and/or second coils 734and 736. First coil 734 may include a first loop portion 740 and asecond loop portion 742, and second coil 736 may include a first loopportion 744 and a second loop portion 746. The first and second loopportions of both coils may have bow tie profiles that taper towards amidpoint between respective first and second loop portions. In suchembodiments, the bow tie loop profiles minimize air gaps between firstand second coils 734 and 736, thereby increasing the efficiency at whichreceiver 711 generates current from magnetic fields. It is to beappreciated that any suitable loop profile for interacting with magneticfields are envisioned herein.

With reference back to FIG. 7A, in embodiments, receiver 710 may alsoinclude a shielding disk 726 positioned on top of first and second coils712 and 714. Shielding disk 726 may have a structure that complementsthe overall structure of first and second coils 712 and 714. Forexample, shielding disk 726 may have a circular structure such that itsouter edges are adjacent to the outer radial edges of first and secondcoils 712 and 714, as shown in FIG. 7A. In embodiments, shielding disk726 may be formed of a ferromagnetic material (e.g., ferrite sheetmaterial) used to concentrate magnetic fields and direct them inaccordance with the selected geometry based upon the arrangement of thereceiver. Shielding disk 726 may be used to guide magnetic fieldsthrough first and second coils 712 and 714; additionally, shielding disk726 may have a thin structure to minimize the size of receiver 710, aswill be discussed further herein with respect to FIG. 7C.

FIG. 7C is a simplified diagram illustrating a cross-sectional view ofreceiver 710 according to an embodiment of the present disclosure. Asshown, first and second coils 712 and 714 may be embedded in a substrate730 disposed below shielding disk 726. Substrate 730 may be any suitablesubstrate capable of housing and electrically isolating embedded coilsof wire. As an example, substrate 730 may be a printed circuit board(PCB). First and second coils 712 and 714 are illustrated as a series ofcircles due to the cross-sectional perspective of the illustration ofFIG. 7C. Accordingly, first loop portion 722 of coil 712 may berepresented by circles 712 a and 712 b, and second loop portion 724 ofcoil 712 may be represented by circles 712 c and 712 d. Second coil 714may be represented by circles 714 a and 714 b, and third coil 716 may berepresented by circles 716 a and 716 b. First, second, and third coilsmay be arranged such that a current may be generated in respective coilsupon interaction with magnetic fields.

In embodiments, at least two of coils 712, 714, and 716 may bepositioned in the same plane. As an example, coils 712 and 716 may bepositioned in the same plane. In other examples, all three coils 712,714, and 716 may be positioned in the same plane. Positioning coils 712,714, and 716 in the same plane enables the structure of receiver 710 tobe substantially low profile, meaning the Z-height of receiver 710 maybe substantially small. For instance, the overall Z-height of receiver710 may be less than a millimeter thick. In an embodiment, the overallZ-height of receiver 710 may be approximately 0.5 mm. In suchembodiments, the thickness of shielding disk 726 may be less than theoverall Z-height of receiver 710. It is to be appreciated that althoughthe thickness of shielding disk 726 is less than the overall Z-height ofreceiver 710, it is not too thin such that it is not capable ofconcentrating and redirecting magnetic fields. An example of suchredirection of magnetic fields is illustrated in FIG. 7D. When amagnetic field 748 propagates at an angle with respect to the plane offirst or second coil 712 or 714, respectively, shielding disk 726 mayredirect magnetic field 748 through its structure. Accordingly, magneticfield 748 may propagate through loops of first and second coils 712 and714 to induce a current in first and second coils 712 and 714. Inembodiments, the thickness of shielding disk 726 may range between 0.2to 0.5 mm. In a particular embodiment, the thickness of shielding disk726 is 0.3 mm.

B. Receiver Operation

According to some embodiments herein, the arrangement of three coilsdisposed about a core in three different directions enables power to begenerated by a receiver in a magnetic field when the receiver is placedin any orientation. FIGS. 8 and 9 illustrate the operation of a receiverwhen placed against a charging surface according to embodiments of thepresent disclosure. Specifically, FIG. 8 illustrates receiver operationin the X and Z directions, and FIG. 9 illustrates receiver operation inthe X and Y directions. The receiver in FIGS. 8 and 9 are illustrated asreceiver 600 in FIG. 6A; however, it is to be appreciated that any othertype of receiver may be used instead. For instance, receiver 710 orreceiver 711 in FIGS. 7A and 7B, respectively, may be used in place ofthe receiver in FIGS. 8 and 9.

As shown in FIG. 8, receivers 801 a-801 d disposed in a dock or anelectronic device (neither of which are not shown for ease ofexplanation) may be placed on a charging surface 811 of a chargingstructure 813. Receiver coils 804 and 806 may be disposed about core 808in the X and Z directions, respectively. Transmitter coils 805 a-805 c,each having loop portions 807 a and 807 b, may generate time-varyingmagnetic fields, such as magnetic fields 809 a-809 e, that extend abovecharging surface 811. Charging structure 813 is illustrated as a tablehaving a substantially planar top surface, but any other chargingstructure 813 may be used. Additionally, transmitter coils 805 a-805 care illustrated as embedded within the table, but may be disposedunderneath charging structure 813 in other embodiments. Each ofreceivers 801 a-801 d is placed in a different location and/ororientation on charging surface 811 to illustrate how the receivers canreceive power from magnetic fields 809 a-809 e.

Receiver 801 a is positioned above a loop portion, e.g., 807 b, of atransmitter coil, e.g., 805 a. Magnetic fields generated by loop portion807 b may include a substantially vertical component, i.e., along theZ-direction. Accordingly, a current may be induced from these fields inreceiver coil 806 a and may be used to generate power. Because themagnetic field may not be substantially disposed along the X-directionat this location, a current may not be generated in receiver coil 804 a,thus causing receiver coil 804 a to generate little to no power.

Receiver 801 c is positioned between transmitter coils 805 b and 805 c.Unlike conventional systems, receiver 804 c can receive power frommagnetic fields disposed between transmitter coils 805 b and 805 c. Asshown, bridging magnetic field 809 d may be disposed between transmittercoils 805 b and 805 c and may include a substantially horizontalcomponent. Accordingly, a current may be induced in receiver coil 804 cand may be used to generate power. Because the magnetic field 809 d maynot be substantially disposed along the Z-direction at this location, acurrent may not be generated in receiver coil 806 c, thus causingreceiver coil 806 c to generate little to no power.

In addition to being placed flush against charging surface 811 togenerate power, receiver 801 can be tilted or even placed on its sideand still generate power. For instance, receiver 801 b is tilted at anangle 810 that is less than 60 degrees (e.g., 45 degrees) to thecharging surface 811. When tilted, currents may be induced by magneticfield 809 c in both receiver coils 804 b and 806 b. In some embodiments,portions of magnetic field 809 d proportionally induce correspondingcurrents in both receiver coils 804 b and 806 b. As angle 810 increasesto a point where it is completely perpendicular to charging surface 811(e.g., the position of receiver 801 d), current may cease to be inducedin receiver coil 804 d, but may be more strongly induced in receivercoil 806 d. Thus, magnetic field 809 e may induce a current in receivercoil 806 d, such that receiver coil 806 d can be used to generate powerfrom magnetic field 809 e. Even though receiver coil 806 d is disposedabout the Z-direction relative to core 808 d, receiver coil 806 d ispositioned about the X-direction relative to charging surface 811.Accordingly, receiver coil 806 d may generate power from magnetic field809 e.

With reference now to FIG. 9, FIG. 9 illustrates receivers 901 a-901 cresting on a charging surface 911 in the X and Y direction. Receivers901 a-901 c may rest on charging surface 911 in different locations andin different orientations. Receiver coils 904 a-904 c and 902 a-902 cmay each be disposed about their respective cores 908 a-908 c in the Xand Y directions, respectively. Transmitter coils 905 a-905 h, eachhaving loop portions 907 a and 907 b, may generate time-varying magneticfields (including magnetic fields 909 a-909 c) that extend abovecharging surface 911. All magnetic fields may operate in concert to formcharging regions 912 a and 912 b which can overlap in some embodiments.In some embodiments, transmitter coils 905 a-905 h may be arranged in anN×M array that is capable of generating a substantially rectangularcharging region. In other embodiments it may be possible to formcircular, oval or other shaped charging regions by arranging coils 905a-905 h in different patterns.

Each of receivers 901 a-901 c is placed in a different location and/ororientation to illustrate how the receiver can generate power frommagnetic fields in charging regions 912 a and 912 b.

Receiver 901 a is positioned between transmitter coils 905 a and 905 b.Unlike conventional systems, receiver 901 a can receive power frommagnetic fields disposed between transmitter coils 905 a and 905 b. Asshown, bridging magnetic field 909 a may be disposed between transmittercoils 905 a and 905 b and may include a substantially horizontalcomponent. Accordingly, a current may be induced in receiver coil 904 aand may be used to generate power. Because magnetic field 909 a may notbe substantially disposed along the Y-direction at this location, acurrent may not be generated in receiver coil 902 a, thus causingreceiver coil 902 a to generate little to no power.

In some embodiments, receivers can also be rotated at an angle less thanor equal to 60 degrees and still generate power. Receiver 901 b isrotated at an angle that is less than 60 degrees (e.g., 45 degrees) tothe X-direction. When rotated, currents may be induced by magnetic field909 b in both receiver coils 902 b and 904 b. In some embodiments, aportion of magnetic field 909 b induces corresponding currents in bothreceiver coils 902 b and 904 b. As the angle increases to a point whereit is completely perpendicular to the X-direction (e.g., the position ofreceiver 901 c), current may cease to be induced in receiver coil 904 c,but may be more strongly induced in receiver coil 902 c. Thus, magneticfield 909 c may induce a current in receiver coil 902 c, such thatreceiver coil 902 c can be used to generate power from magnetic field909 c. Even though receiver coil 902 c is disposed about the Y-directionrelative to core 908 c, receiver coil 902 c is positioned about theX-direction relative to charging surface 911. Accordingly, receiver coil902 c may generate power from magnetic field 909 c.

Although embodiments illustrate receivers 901 a-901 c located betweentransmitter coils 905 a-905 h, any of receivers 901 a-901 c may beplaced in regions above transmitter coils 905 a-905 h to generate poweras well. For instance, receiver 901 c may be placed on transmitter 905 csuch that receiver 901 c may generate power from magnetic field 909 d.

Accordingly, as shown in FIGS. 8 and 9, receivers discussed herein maygenerate power in any orientation on a charging surface, according toembodiments of the present disclosure. This allows a docking station orelectronic device, embedded with such a receiver, to not have to beplaced above a transmitter coil in any particular orientation in someembodiments.

It should also be noted that in some embodiments, only certaintransmitter coils 905 a-905 h that are close enough to a receiver, e.g.,any of receivers 901 a-901 c, can be selectively energized to generate amagnetic field that induces a current in at least one of the coils ofthe receiver. A location of the receiver with respect to transmittercoils 905 a-905 h can be determined in any number of ways. In someembodiments, charging surface 911 can include a sensor configured toidentify a location and orientation of an electronic device within whichthe receiver is housed. For example, a capacitive sensor can beconfigured to detect contact between a housing of the electronic deviceand the capacitive sensor. In some embodiments, a power expenditure canbe measured when all of transmitter coils 905 a-905 h are energized andthen only those transmitter coils 905 a-905 h with the largestvariations caused by interaction with a receiving coil of an electronicdevice can remain energized.

One such example is shown in FIG. 10. Specifically, FIG. 10 illustratesan exemplary charging surface 1000 configured to enable selectiveenergizing of transmitter coils 1005 a-1005 h. Charging surface 1000 canbe part of a wireless charging table, such as charging structure 500shown in FIG. 5 or table 800 shown in FIGS. 8 and 9 or can be part of awireless charging mat or other wireless charging structure. As shown inFIG. 10, charging surface 1000 may include transmitter coils 1005 a-1005h and a plurality of sensors 1022 a-1022 h. Charging surface 1000 mayalso include a power distribution system 1007 configured to receivepower from an alternating current (AC) power source 1021 (e.g, from awall outlet) and distribute the AC power to one or more transmittercoils 1005 a-1005 h. In embodiments, the power distribution systemincludes a controller 1020 coupled to transmitter coils 1005 a-1005 hand sensors 1022 a-1022 h. Controller 1020 may be configured to receiveinformation from sensors 1022 a-1022 h and/or transmitter coils 1005a-1005 h and control the operation of transmitter coils 1005 a-1005 h inresponse to the received information. Sensors 1022 a-1022 h can be anytype of sensor that enables the charging surface to detect the presenceand location of one or more electronic devices, such as electronicdevices 1004 and 1006 on the charging surface. As one example, sensors1022 a-1022 h can be capacitive sensors.

As shown in FIG. 10, individual electronic devices to be charged can beplaced at various locations on charging surface 1000. Sometimes a devicemay be placed directly over or very near an individual coil—illustratedin FIG. 10 as device 1004 placed directly over coil 1005 c. At othertimes a device may be placed in between two or more coils—illustrated inFIG. 10 as device 1006 placed between coils 1005 g and 1005 h. In thefirst situation, the presence of electronic device 1004 can be detectedby sensor 1022 c and cause sensor 1022 c to send information tocontroller 1020. Controller 1020 can then use this information anddetermine that transmitter 1005 c should be turned on to provide powerto device 1004, as transmitter 1005 c is closest to electronic device1004. In the second situation, the presence of electronic device 1006can be detected by both sensors 1022 g and 1022 h, each of which cansend information to controller 1020, which may then use the informationto determine that transmitter 1005 g and 1005 h should be turned on toprovide power to device 1006.

Once presence of the electronic device is detected, one or moreverification procedures may be performed to ensure that the electronicdevice is a device that is suitable for receiving power from thetransmitter coils. For instance, after detecting the presence of theelectronic device, a communication channel may be established betweencontroller 1020 and one or more electronic device, e.g., electronicdevices 1004 and 1006. The electronic device may then be queried for itsidentification to verify that the device is suitable for receiving powerfrom the transmitter coils. After receiving and verifying theidentification of the electronic device, magnetic fields may begenerated by transmitter coils close enough to the electronic device. Ifno communication channel can be established with the electronic device,then it may be determined that the electronic device is in fact not anelectronic device, or not an electronic device that is suitable forreceiving power from the transmitter coils. In which case, notransmitter coils may be activated to generate magnetic fields to theelectronic device. Performing verification procedures ensures thatmagnetic fields are not generated for objects that are not electronicdevices that can receive the generated magnetic fields, and ensures thatif the object is an electronic device, it is an electronic device thatis configured to receive the generated magnetic fields. In this way, noadditional energy need to be expended energizing transmitter coils thatare not being utilized.

IV. Stacked Transmitter and Receiver Coils

In certain embodiments, transmitter coils may be stacked upon oneanother to provide a continuous charging region with minimal dead zones.FIG. 11 is a simplified diagram illustrating a top-down view of astacked transmitter 1102 according to embodiments of the presentdisclosure. The structure, current flow, and generation of magneticfields may be similar to transmitter coil 200 discussed herein withrespect to FIG. 2A. Stacked transmitter 1102 may include a firsttransmitter coil 1104 and a second transmitter coil 1106 positioned overat least a portion of first transmitter coil 1104. First and secondtransmitter coils 1104 may each be a transmitter coil having anysuitable transmitter profile discussed herein, such as a bow tieprofile, bent L-shaped profile, or a rectangular profile as shown inFIG. 11.

First and second transmitter coils 1104 and 1106 may be horizontallyoffset from one another by a distance D, which may be selected to be adistance that enables stacked transmitter 1102 to generate overlappingmagnetic fields to form a charging region, e.g., charging regions 912 aand 912 b in FIG. 9, with minimal dead zones. In an embodiment, distanceD is a fraction of an entire width of a transmitter coil. For instance,distance D is a quarter of a width W of first transmitter coil 1104.Although FIG. 11 shows first and second transmitter coils 1104 and 1106offset from one another in a horizontal direction, embodiments are notso limited. First and second transmitter coils 1104 and 1106 may beoffset from one another in a horizontal direction, vertical direction,or both horizontal and vertical directions, as long as at least aportion of second transmitter coil 1106 overlaps a portion of firsttransmitter coil 1104.

FIG. 12 is a simplified diagram illustrating a cross-sectional view ofan exemplary stacked transmitter 1202 and the interaction of itsgenerated magnetic fields with a receiver 1208 placed in variouspositions. As shown, receiver 1208 is placed in three positions: firstreceiver position 1210, second receiver position 1212, and thirdreceiver position 1214. It is to be appreciated that although FIG. 12illustrates the three receiver positions stacked upon one another, it isnot intended to disclose that receiver 1208 includes three individualreceiver stacked upon one another. Rather, it is intended to disclosethat receiver 1208 is a single receiver that can be placed in threereceiver positions that are offset from one another in the horizontaldirection, i.e., translationally offset from one another, within thesame horizontal plane.

In embodiments, stacked transmitter 1202 may include a ferrite shield1203 and two transmitter coils: a first transmitter coil 1204 and asecond transmitter coil 1206. Second transmitter coil 1206 may overlapat least a portion of first transmitter coil 1204. Each coil may beembedded within a flexible substrate 1205, such as a printed circuitboard. In embodiments, first transmitter coil 1204 may be operated at afrequency that is orthogonal to the frequency at which secondtransmitter coil 1206 operates such that magnetic fields generated byfirst transmitter coil 1204 propagate in an opposite direction tomagnetic fields generated by second transmitter coil 1206. In theexample shown in FIG. 12, first transmitter coil 1204 may operate in the0° and 180° phases while second transmitter coil 1206 may operate in the90° and 270° phases. In some embodiments, stacked transmitter 1202 maybe carrying significant current during operation. Thus, dimensions offerrite shield 1203 may affect ferrite losses incurred by stackedtransmitter 1202. In particular embodiments, increasing a thickness offerrite shield 1203 and/or increasing separation between ferrite shield1203 and first transmitter 1204 may minimize ferrite losses. In certainembodiments, the thickness of ferrite shield 1203 may range between 3-5mm, and the separation may range between 15 to 25 mm. In an embodiment,the thickness of ferrite shield 1203 is approximately 4 mm, and theseparation is approximately 20 mm.

When receiver 1208 is placed in any one of receiver positions 1210,1212, and 1214, a corresponding current may be generated in one or morecoils of the receiver when interacting with the magnetic fieldsgenerated by stacked transmitter 1202. The phase of the generatedcurrent in receiver 1208 may depend on the position of receiver 1208relative to stacked coils 1204 and 1206 in stacked transmitter 1202. Asan example, when receiver 1208 is placed in first receiver position1210, receiver 1208 may be vertically aligned with first transmittercoil 1204 such that the phases of the generated current in receiver 1208are 0° and 180°. When receiver 1208 is placed in second receiverposition 1212, receiver 1208 may be vertically aligned with secondtransmitter coil 1206 such that the phases of the generated current inreceiver 1208 are 90° and 270°. Additionally, when receiver 1208 isplaced in third receiver position 1214, receiver 1208 may be verticallypositioned between first and second transmitter coils 1204 and 1206 suchthat the phases of the generated current in receiver 1208 are 45° and225°.

In addition to stacking transistor coils as discussed herein withrespect to FIG. 11, a receiver may also include stacked receiver coils,as shown in FIG. 13. FIG. 13 is a simplified diagram of a stackedreceiver 1300 having a first receiver coil 1302 and a second receivercoil 1304 overlapping first receiver coil 1302. Similar to receiver 710,each receiver coil 1302 and 1304 may include first and second loopportions for receiving magnetic fields. In embodiments, first and secondreceiver coils 1302 and 1304 may be centered with one another andoriented at an offset angle. The degree of offset angle may be selectedto maximize current generation when stacked receiver 1300 is positionedin magnetic fields generated by a transmitter, such as stackedtransmitter 1102 in FIG. 11. As an example, the degree of offset anglemay be 90° such that a center line 1303 of first coil 1302 isperpendicular to a center line 1305 of second coil 1304. It is to benoted that any other degree of offset angle is envisioned herein tomaximize generation of current in transmitter coils 1302 and 1024 whenpositioned in a magnetic field.

FIG. 14 is a simplified diagram illustrating a charging system 1400including stacked receivers 1402 and 1404 positioned over a plurality ofstacked transmitter coils 1405. Stacked receivers 1402 and 1404 may eachinclude two overlapping receiver coils that are positioned at a 90°offset angle from one another. For instance, stacked receiver 1402 mayinclude a first receiver coil 1406 and a second receiver coil 1408, andstacked receiver 1404 may include a first receiver coil 1410 and asecond receiver coil 1412. Stacked receivers having this coilarrangement are capable of receiving power from stacked transmittercoils 1405 in different rotational orientations. Depending on the angleof rotation, one or both receiver coils of the stacked receiver may bereceiving power. For instance, if a stacked receiver is positioned at anangle that is a multiple of 90° with respect to stacked transmittercoils 1405, one of its receiver coils will receiver power. If thestacked receiver is positioned in any other angle that is not a multipleof 90°, then both of its receiver coils may receiver power.

As shown in FIG. 14, stacked receiver 1402 is positioned parallel tostacked transmitter coils 1405, which is an angle that is a multiple of90° . Thus, one receiver coil, e.g., receiver coil 1406 of stackedreceiver 1402, will receive power from stacked transmitter coils 1405.Stacked receiver 1404, is positioned at an angle that is not a multipleof 90° with respect to stacked transmitter coils 1405. As shown in FIG.14, stacked receiver 1404 is positioned at an angle of 45° with respectto stacked transmitter coils 1405. Thus, both first and second receivercoils 1410 and 1412 may receiver power from stacked transmitter coils1405.

V. Method of Forming Receiver

FIG. 15 illustrates a flow chart for fabricating a wireless chargingreceiver according to some embodiments of the present disclosure. Atblock 1502, a core, such as core 608 in FIG. 6A, may be provided. Insome embodiments, the core may be a ferromagnetic core that canconcentrate magnetic fields. The core may be in the shape of arectangular prism, or any other shape suitable for maximizingconcentration of magnetic fields and compatible with desired coilgeometries.

At block 1504, a first insulating layer may be formed around the core.In some embodiments, the insulating layer may be a dielectric filmhaving a dielectric constant suitable to electrically isolate conductivematerials from one another. The insulating layer may be formed by alamination process that presses a layer of insulating film around thecore and subsequently cures the insulating film. In other embodiments,the insulating layer may be formed by fusing a first set of two halvestogether. The two halves may each be a shell formed of an insulatingmaterial shaped to cover half of an underlying structure, such as thecore. When the two halves are fused together, an insulating layer may beformed around the entire core.

At block 1506, a first coil may be formed on the first insulating layer.The first coil may be any of the three coils 602, 604, and 606 describedherein with respect to FIG. 6A. In some embodiments, the first coil maybe formed by any suitable patterning process. For instance, the firstcoil may be formed by a Laser Direct Structuring (LDS) process. In otherembodiments, the first coil may be formed by depositing and etching apatterned seed layer and subsequently performing an electroplatingprocess to build up the structure of the first coil. One skilled in theart will understand that any process capable of patterning a coil on aninsulating layer may be utilized in embodiments herein.

At block 1508, a second insulating layer may then be formed on the firstcoil and exposed surfaces of the first insulating layer. As describedherein, the second insulating layer may be laminated or may be formed byfusing a second set of two halves of insulating shells. Thereafter, atblock 1510, a second coil may be formed on the second insulating layer.The second coil may be any of the three coils 602, 604, and 606described herein with respect to FIG. 6A. The second coil may be formedby any suitable deposition or patterning process such as those describedherein with respect to forming the first coil.

Once the second coil is formed, at block 1512, a third insulating layermay be formed on the second coil and exposed surfaces of the secondinsulating layer. Similar to first and second insulating layers, thethird insulating layer may be laminated or formed by fusing a third setof two halves of insulating shells. Then, at block 1514, a third coilmay be formed on the third insulating layer. The third coil may be anyof the three coils 602, 604, and 606 discussed herein with respect toFIG. 6A, and may be formed by any suitable deposition or patterningprocess described herein with respect to forming the first and secondcoils.

Optionally, a fourth insulating layer may be formed over the third coiland exposed surfaces of the third insulating layer to electricallyinsulate the third coil and/or protect the third coil from damage duringsubsequent fabrication steps. The fourth insulating layer may preventinadvertent shorting between the third coil and other conductivestructures. That way, the receiver may be properly protected andinsulated from the external environment.

VI. Method of Charging a Device

FIG. 16 illustrates a flow chart 1600 for charging an electronic deviceaccording to embodiments of the present disclosure. At block 1602, acharging surface including transmitter having a plurality of transmittercoils may be provided. The plurality of transmitter coils may bedisposed below the charging surface and may be configured to generate aplurality of magnetic fields in more than one direction when a currentis supplied. The generated magnetic fields may penetrate through thecharging surface such that the magnetic fields exist above the chargingsurface and are accessible to the electronic device when placed on thecharging surface. In some embodiments, a single AC (or pulsed DC) powersource and clock may be used to drive the plurality of transmittercoils.

At block 1604, the electronic device may be placed on the chargingsurface. The electronic device may contain a receiver having a core anda plurality of receiver coils disposed about the core in differentdirections. The receiver may be configured to receive power from anyorientation when placed in a magnetic field.

Once placed on the charging surface, at block 1606, the electronicdevice may be left on the charging surface such that at least one of theplurality of magnetic fields induces a current in at least one of theplurality of receiver coils. For instance, a magnetic field may induce acurrent in two coils: one coil being disposed about a Y-direction, andanother coil being disposed about an X-direction. The current may berectified in the electronic device and then used to charge an internalbattery.

After a desired amount of charge has been stored on the battery, then atblock 1606, the electronic device may be removed from the chargingsurface. In some embodiments, the electronic device can be coupled to adocking station that includes the receiver, and that performs some orall of the functions performed by the electronic device described hereinwith respect to flow chart 1600.

Although the disclosure has been described with respect to specificembodiments, it will be appreciated that the disclosure is intended tocover all modifications and equivalents within the scope of thefollowing claims.

What is claimed is:
 1. A wireless charging table comprising: a table tophaving an upper surface upon which one or more electronic devices can beplaced; a wireless charging transmitter positioned under the uppersurface of the table top, the wireless charging transmitter comprising aplurality of transmitter coils that define a charging region at theupper surface of the table top, the plurality of transmitter coilsincluding at least a first transmitter coil comprising: a first loopportion; a second loop portion; and a crossing portion comprisingoverlapping conductive paths that electrically couple the first loopportion and the second loop portion such that, when an electricalcurrent is generated in the first transmitter coil, the electricalcurrent flows through the first loop portion in a first rotationaldirection, and through the second loop portion in a second rotationaldirection opposite the first rotational direction; and a powerdistribution system operatively coupled to the wireless chargingtransmitter, the power distribution system configured to receive powerfrom an alternating current (AC) power source and distribute power tothe wireless charging transmitter.
 2. The wireless charging table ofclaim 1 wherein when the electrical current is generated in the firsttransmitter coil: a first magnetic field is generated by the currentflowing through the first loop portion, the first magnetic field beingcharacterized by a first direction; and a second magnetic field isgenerated by the current flowing through the second loop portion, thesecond magnetic field being characterized by a second directiondifferent than the first direction.
 3. The wireless charging table ofclaim 2 wherein an angle formed between the first direction and thesecond direction is at least 135 degrees.
 4. The wireless charging tableof claim 1 wherein the crossing portion is a first crossing portion, andwherein the plurality of transmitter coils further comprises a secondcoil configured to transmit power, the second coil comprising: a thirdloop portion; a fourth loop portion; and a second crossing portioncomprising overlapping conductive paths that electrically couple thethird loop portion and the fourth loop portion such that, when anelectrical current is generated in the second coil, the electricalcurrent flows: through the third loop portion in the first rotationaldirection; and through the fourth loop portion in the second rotationaldirection.
 5. The wireless charging table of claim 4 wherein when theelectrical current is generated in the first transmitter coil and thesecond coil, a bridging magnetic field is generated in a region betweenthe first transmitter coil and the second coil.
 6. The wireless chargingtable of claim 5 wherein the bridging magnetic field bends between thesecond loop portion and the third loop portion.
 7. The wireless chargingtable of claim 1 wherein the first loop portion has a first horizontalpart and a first vertical part, and the second loop portion has a secondhorizontal part and a second vertical part.
 8. The wireless chargingtable of claim 7 wherein the first horizontal part extends above thesecond vertical part, and wherein the second horizontal part extendsbelow the first vertical part.
 9. The wireless charging table of claim1, wherein the power distribution system includes a controllerconfigured to communicate with an electronic device of the one or moreelectronic devices.
 10. A wireless charging receiver for interactingwith a wireless charging retail table comprising: a first coil disposedrelative to a first axis; a second coil disposed relative to a secondaxis, the second axis extending in a direction different than the firstaxis; and a ferromagnetic structure positioned adjacent to the firstcoil and the second coil, wherein the first coil, the second coil, andthe ferromagnetic structure are configured to receive magnetic fieldsgenerated by a transmitter for the wireless charging retail table. 11.The wireless charging receiver of claim 10, wherein the wirelesscharging receiver is encased within a docking station.
 12. The wirelesscharging receiver of claim 11, wherein the docking station is configuredto rest on a charging surface of the wireless charging table.
 13. Thewireless charging receiver of claim 11, wherein the docking station isconfigured to connect to an electronic device to provide power to theelectronic device.
 14. The wireless charging receiver of claim 10further comprising a third coil disposed relative to a third axis, thethird axis extending in a direction different than the first axis andthe second axis.
 15. The wireless charging receiver of claim 14 whereinthe second axis is perpendicular to the first axis, and wherein thethird axis is perpendicular to the first axis and the second axis.
 16. Awireless charging system comprising: a table top having an upper surfaceupon which one or more electronic devices can be placed; a wirelesscharging transmitter positioned under the upper surface of the tabletop, the wireless charging transmitter comprising a plurality oftransmitter coils that define a charging region at the upper surface ofthe table top, the plurality of transmitter coils including at least afirst transmitter coil comprising: a first loop portion; a second loopportion; and a crossing portion comprising overlapping conductive pathsthat electrically couple the first loop portion and the second loopportion such that, when an electrical current is generated in the firsttransmitter coil, the electrical current flows through the first loopportion in a first rotational direction, and through the second loopportion in a second rotational direction opposite the first rotationaldirection; and a power distribution system operatively coupled to thewireless charging transmitter, the power distribution system configuredto receive power from an alternating current (AC) power source anddistribute power to the wireless charging transmitter; and a wirelesscharging receiver comprising: a first coil disposed relative to a firstaxis; a second coil disposed relative to a second axis, the second axisextending in a direction different than the first axis; and aferromagnetic structure positioned adjacent to the first coil and thesecond coil, wherein the first coil, the second coil, and theferromagnetic structure are configured to receive magnetic fieldsgenerated by the plurality of transmitter coils.
 17. The wirelesscharging system of claim 16, further comprising: a plurality of sensorsconfigured to detect a presence of an electronic device.
 18. Thewireless charging system of claim 17, wherein the power distributionsystem comprises a controller coupled to the plurality of sensors andthe plurality of transmitter coils.
 19. The wireless charging system ofclaim 18, wherein the controller is configured to selectively energizeone or more transmitter coils in response to the detected presence ofthe electronic device.
 20. The wireless charging system of claim 16,wherein the wireless charging receiver is encased within a dockingstation.